Lymphocyte-Monocyte Ratio (LMR) Calculator
Lymphocyte-Monocyte Ratio (LMR) Calculator
Calculate the lymphocyte-monocyte ratio — and read the honest caveat with it. There is no reference interval and no agreed cut-off; every published threshold was chosen from a single study's own data.
Lymphocyte-Monocyte Ratio (LMR)
ALC ÷ AMCALC 1.8 ×10⁹/L, AMC 0.55 ×10⁹/L
Formula
- ALC
- absolute lymphocyte count, ×10⁹/L
- AMC
- absolute monocyte count, ×10⁹/L
- no reference interval
- unlike either of its components, the ratio has no population-derived normal range. Nothing here is a reference interval
- study-specific cut-offs
- published thresholds are chosen by ROC analysis on each study's own cohort, so they optimise that dataset and do not transfer
Worked example
ALC 1.8 ×10⁹/L, AMC 0.55 ×10⁹/L
1.8 ÷ 0.55 = 3.27
That sits just above 3.0, the median cut-off across 33 solid-tumour studies, whose individual cut-offs ranged from 2.0 to 5.3
Which is a statement about the literature, not about this patient
There is no reference interval for LMR, so this result should not be reported as normal or abnormal
What is and is not known about the LMR
| Question | Answer |
|---|---|
| Is there a reference interval? | No. None has been established in a healthy population |
| Is there an agreed cut-off? | No. Each study derives its own, usually by ROC analysis on its own cohort |
| What range do the published cut-offs span? | In solid tumours, a median of 3.0 with a range of 2.0 to 5.3 across 33 studies |
| Which direction is adverse? | A low ratio. High lymphocytes with low monocytes is the favourable combination |
| Is it in any guideline? | No. It is not a diagnostic, staging or treatment criterion anywhere |
| What is it good for? | Research, and as one variable among many in prognostic models — not as a result to act on |
Why the ratio moves
| Component | Rises with | Falls with |
|---|---|---|
| Lymphocytes (numerator) | Recovery, viral infection, chronic lymphocytic leukaemia | Corticosteroids, acute stress, chemotherapy, HIV, advanced malignancy |
| Monocytes (denominator) | Chronic infection and inflammation, recovery from neutropenia, tumour-associated macrophage biology | Corticosteroids in the first hours, hairy cell leukaemia, aplastic anaemia |
| The ratio | Anything raising lymphocytes or lowering monocytes | Anything lowering lymphocytes or raising monocytes |
A number with no normal range, and why that has to be said out loud
The lymphocyte-monocyte ratio is the absolute lymphocyte count divided by the absolute monocyte count. The arithmetic is trivial and the interpretation is where honesty is required: there is no established reference interval for the LMR and no agreed cut-off. It is a research and prognostic measure, studied mostly in lymphoma and in solid tumours, and it has not been adopted as a diagnostic, staging or treatment criterion in any guideline. Nothing on this page should be read as a normal range.
The published thresholds illustrate the problem rather than solving it. A systematic review of solid-tumour studies found a median cut-off of 3.0 with a range from 2.0 to 5.3 across the included cohorts, and the reason for that spread is methodological: each study chose its own threshold by receiver-operating-characteristic analysis on its own dataset, selecting the value that best separated outcomes in that particular group of patients. A cut-off derived that way is optimised for the cohort it came from and is not expected to transfer, which is exactly why so many different ones exist.
The biological rationale is real, which is what makes the measure interesting rather than arbitrary. Lymphocytes represent the adaptive, tumour-directed arm of the immune response, and circulating monocytes are the precursors of tumour-associated macrophages, which support tumour growth and suppress that response. A ratio that combines them therefore moves with something meaningful. But both arms also move with corticosteroids, acute illness, chemotherapy and simple physiological stress, so a single value says nothing about when the sample was taken or what was happening that day.
The practical position is that the LMR is a legitimate variable in a research dataset or a multivariable prognostic model, and is not a test result to act on. It should not be used to decide whether someone has a disease, to trigger imaging or a referral, or to reassure. Where a genuine question about the white cells exists, the absolute lymphocyte and monocyte counts and a blood film answer it better than their quotient, because a ratio of 3.3 is produced equally by an ALC of 1.8 with an AMC of 0.55 and by an ALC of 0.33 with an AMC of 0.1, and those two patients have nothing in common.
Frequently asked questions
What is a normal lymphocyte-monocyte ratio?
There is no established normal range. No reference interval has been derived in a healthy population, and the thresholds in the literature are study-specific cut-offs rather than population norms. Any source quoting a single normal value is overstating what is known.
What LMR is considered low?
It depends entirely on the study. A systematic review of solid tumours found published cut-offs with a median of 3.0 and a range from 2.0 to 5.3. Each was chosen by ROC analysis on its own cohort, so none of them generalises.
Is the LMR used in clinical practice?
Not as a diagnostic or treatment criterion. It appears in prognostic research, especially in lymphoma and solid tumours, but it is not part of any staging system, guideline or management algorithm, and it should not drive a clinical decision on its own.
Why might the LMR predict outcome in cancer?
Lymphocytes represent the adaptive anti-tumour response and circulating monocytes are precursors of tumour-associated macrophages, which suppress it. The ratio combines the two arms. But it also moves with steroids, acute illness and chemotherapy, which limits what a single value means.
Should I be worried about a low LMR?
Not on the basis of the ratio itself. It has no reference interval and no validated threshold, so a low value is not an abnormal result. If the underlying lymphocyte or monocyte counts are abnormal, those counts — and a blood film — are what should be looked at.
Related calculators
References
- Nishijima TF, Muss HB, Shachar SS, Tamura K, Takamatsu Y. Prognostic value of lymphocyte-to-monocyte ratio in patients with solid tumors: a systematic review and meta-analysis. Cancer Treat Rev. 2015;41(10):971–978.
- Porrata LF, Ristow K, Colgan JP, et al. Peripheral blood lymphocyte/monocyte ratio at diagnosis and survival in classical Hodgkin’s lymphoma. Haematologica. 2012;97(2):262–269.